The usual method of manufacturing a vehicle seat cover involves cutting out shaped pieces of woven fabric intended to make the seat cover and subsequently sewing these pieces together to form the base and back covers, fashioning lines being introduced in some areas of the fabric if necessary. It is also necessary to provide anchorage devices at the edges of the base and back covers to enable attachment of the covers to respective cushions. Usually these anchorage devices take the form of hollow sewn hems through which a retaining member such as a metal rod or a tape can be threaded for securing the cover to the seat frame. An example of this type of arrangement is shown in U.S. Pat. No. 2,811,199.
If the base and/or back cushions comprise bolsters, it is also necessary to provide anchorage devices, usually in the form of open looped flaps, on the undersurface of the cover, in order to conform the cover to the shape of the upper surface of the cushion. U.S. Pat. No. 2,801,682 shows a loop of fabric formed by a sewing operation on the undersurface of a fabric cover for a vehicle seat. This fabric loop provides an attachment point for tensioning tapes which pass through the seat. upholstery and pull the fabric loop down into the upholstery to define an indented bolster line.
The conventional manufacture of vehicle seat covers from woven fabric using cut and sew techniques both for shaping the cover and providing anchorage devices is labour-intensive, time-consuming and therefore very costly. It is also wasteful in fabric usage.
The stretch properties of knitted fabric have been employed in furniture upholstery to provide stretch covers which, for a basic shape of chair or sofa, can accommodate variations in size and shape of the customer's furniture. Belgian Patent No. 668,983 describes such stretch covers which are formed using sewing techniques both for shaping purposes and for providing sewn hems at the cover edges through which a tie cord can be threaded. Stretch covers of this type, knitted in highly stretchable single jersey fabric, are unsuitable for vehicle seat upholstery because they do not approach the standards in appearance or performance expected of conventional woven fabric covers, in particular being susceptible to distortion and bagging in use.
Recently, it has been found possible to knit one-piece upholstery fabrics which, without the need for sewing portions together, have the desired shapes to serve as covers for the base and back cushions of a vehicle seat. An aim of the present invention is to provide such a piece of knitted upholstery fabric in a form which facilitates its attachment to a three-dimensional support, such as a vehicle seat cushion.
Knitted fabric is characterized by intermeshing loops of yarn. Intermeshing of loops occurs along the wales of knitted fabric from course to course and also along the courses from wale to wale and creates integrity of the structure in both directions.